Signals necessary for cell growth, differentiation, response to bioregulatory molecules, infectious agents and physiological stress involve changes in the rates of gene expression. The ability to respond appropriately to such signaling events challenge the survival of the cell and ultimately the organism. Perturbations in the normal regulation of these specific genetic responses can result in pathogenic events which lead to acute and chronic disease.
In certain autoimmune diseases or chronic inflammatory states, continuous activation of T-cells eventually leads to a self-perpetuating destruction of normal tissues or organs. This is caused by the induction of adhesion molecules, chemotaxis of leukocytes, activation of leukocytes and the production of mediators of inflammation. All of these events are regulated at the level of transcription for the production of new proteins, including cytokines. The production of cytokines, as well as a number of other cellular regulators, is controlled by a family of proteins known as transcription factors (TFs). These transcription factors, when activated, bind to specific regions on the DNA and act as molecular switches or messengers to induce or upregulate gene expression. The activation of these TFs is caused by a variety of external signals including physiological stress, infectious agents and other bioregulatory molecules. Once the plasma membrane receptors are activated, a cascade of protein kinases and second messengers are induced which, in turn, result in the production of RNA transcripts. The end result is the production of proinflammatory proteins via translation and processing of the RNA transcripts.
This activation system can, at times, be very robust. For example, a specific set of external signals could result in a single transcription factor to induce many proteins responsible for a given disease. Therefore, regulating this process by disrupting the production of activated TF(s) has the potential to attenuate the production of the associated pathological proteins, thereby halting or reversing the course of the disease.
Two transcription factors, NF.kappa.B and AP-1, have been shown to regulate the production of many proinflammatory cytokines and related proteins that are elevated in immunoinflammatory diseases. These TFs regulate interleukin-1 (IL-1), interleukin-2 (IL-2), tumor necrosis factor-.alpha. (TNF.alpha.), interleukin-6 (IL-6) and interleukin-8 (IL-8) levels in a variety of cell types. For example, NF.kappa.B and other related complexes are involved in the rapid induction of genes whose products function in protective and proliferative responses upon exposure of cells to external stimuli. Similarly, AP-1 has a significant role in the regulation of interleukin-2 (IL-2) and tumor necrosis factor-.alpha. (TNF-.alpha.) transcription during T-cell activation. In addition, TNF-.alpha. and IL-1 are strong activators of collagenase, gelatinase and stromelysin gene expression, which require a single AP-1 binding site in the promoter region of these genes. Therefore, an inhibitor of NF.kappa.B and/or AP-1 activation would coordinately repress the activities of a series of proteinases. In addition, cell adhesion molecules are also controlled by these TFs. All of these proteins have been shown to play a role in diseases, including osteoarthritis, transplant rejection, ischemia, reperfusion injury, trauma, certain cancers and viral disorders, and autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, psoriasis, inflammatory bowel disease, glomerulonephritis, lupus and juvenile diabetes. In summary, the role of these TFs is to act as a transducer for certain stimuli that lead to immune, inflammatory, and acute phase responses.
Since many diseases are caused by the inappropriate production of proteins, conventional therapeutic approaches have focused on inhibiting function or activity of individual effector proteins. These treatments have not always proved to be effective and, at times, are associated with many undesirable side effects. Therefore, there is a need for new therapies for the prevention and/or treatment of immunoinflammatory and autoimmune diseases. More specifically, there is a need for compounds that prevent, preferably by inhibiting transcription at an early stage, the production of proteins associated with immunoinflammatory and autoimmune diseases. Furthermore, these compounds should inhibit the kinase(s) that regulate the activation of TFs such as NF.kappa.B and AP-1. The present invention fulfills these needs and provides further related advantages.